Method of producing metal rims



7 June 3 1924. 1,496,362

K. B6HLE METHOD OF PRODUCING METAL RIMS v filed March a. 1921 t) f 'i4.. xx F i;..E5. 3 v *1 H5 m 2 III I /94 Fig 2 LS 5 A B Patented June 3,192

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KARL BI-ILE, O3? ESSEH, GERJVIANY, ASSIGNOIL TQ KRUPP AKTIENGESELL-SCI-IA'ET, F ESSEN-ON-THE-RUHR, GERMANY.

METHOD OF PRODUCING METAL RIMS.

To all whom it may concern:

Be it known that I, KARL BoHLn, residing at Essen, Germany, a citizen ofthe German Republic, have invented a certain new and 5 usefulImprovement in Methods of Produo ing Metal Rims, of which the followingis a specification. My invention relates to a method ofproducing soliddrawn cylindrical rims from flat metal rings which will render itpossible to manufacture rims of the type specified on a drawing press inthe course of a single working operation.

In the drawing atlixed to this specification and forming part thereof,the manner of carrying my invention into practical effect is illustratedin a purely diagrammatic manner by way of example. In the drawing v Fig.l is a sectional View of the metal ring destined for the production of arim, Fig. 2 is a similar view of the rim when ready made,

Figs. 3 and 1 are axial sections through a drawing press and theworkpiece showing the results of the pressing operations where bothworkpiece and drawing press have been.

dimensioned on other lines than those laid down by myinvention, 1

Figs. 5 to 7 are similar views showing the results of the pressingoperation carried outin accordancewith my invention.

A- seamless cylindrical rim B (Fig. 2) may be produced out of aflatmetal ring A (Fig. 1) on the drawing press, provided the possibilitybe givenby a suitable cooperation of the stamp and die of the press-ofeach section of ring A being turned or twisted by 90 relatively to itsinitial position. To this end a press is required, the stamp of which isfitted with a cylindrical part,

corresponding to the inside diameter of the rim, and a conical memberlocated in front of said cylindrical part.

However, as experiments have shown it will prove impossible to producethe rim on such a press whenever the metal ring and the press itself aredimensioned along lines which are not in accordance with my invention,as will be understood from the following explanations with due referenceto Figs. 3 and 4.

On the stamp C (Fig. 3) being lowered, the conical section c -of saidstamp first of all enters the opening of the metal ring A,

Application filed March 3, 1921. Serial No. 449,559.

alterations of this description the workpiece offers definiteresistance, in addition to which there come to arise between theworkpiece and the conical member 0 of the stamp, on the one hand, andbetween the .vorkpiece and the die, on the other hand certain frictionalforces which oppose the lowering of the stamp. Now whenever the forcetransmitted by the stamp to the workpiece, and which strives to draw theworkpiece down into the die, prove to be greater than the resistance,which the workpiece opposes to being thus drawn down, then, as disclosedin Fig. 3, the workpiece A will come to cleave to the conical section 0of the stamp and will be drawn through the die D without any materialalteration of its cross section. Again, wherethe conditions happen to bereversed, and where the resistance offered by the workpiece againstbeing drawn down into the die is the more powerful, the workpiece A willnot be even completely drawn down into the die but will, as Fig. 4discloses, obtain a cylindrical shape only at one portion of itscircumference. From the foregoing explanations it will be understoodthat the production of cylindrical rims from fiat metal rings can onlybe successfully accomplished provided the force brought to act upon theworkpiece, by the stamp, and which tends to draw the workpiece down intothe die, will always and up to the moment when the conical section ofthe stamp passes out of the workpiece be approximately so big that itwill come to be counterbalanced by the resistance to be overcome whendrawing the workpiece through the die.

It is on an appreciation of these facts that the improved method isbased. For experience has demonstrated that the conditions above setforth can only be created on the inside and outside diameters of theworkpiece employed being disposed in a certain definite relation to thediameter of the bore of the die. If, for example, D (in Fig. 1) denotethe outside diameter of the workpiece, 'h the width of the ring, and d(Fig. 3) the diameter of the bore of the die, then, whenever it is aquestion of producing iron rims, the value of D must be disposed wlthinthe hnnts created by the formulae.

lvloreover, the trigonometrical tangent of the angle of inclinationpertaining to the shell lines of the conical portion of the stamprelatively to its base, will obtain a value from 6 to 7, correspondingto angles of inclination of from about 80 to 83F.

In the improved drawing press disclosed in Figs. 5 to 7 and destined topractically realize the above-described novel'method, E

denotes the stamp, e the cylindrical and e the conical part thereof. Thedie F is provided with an annular opening f Serving for theaccommodation of the ring shaped 2 workpiece A. The diameter of theopening the stamp E being lowered, the conical part c thereof enters theopening left in the workpiece A and enlarges it. At the same time, bythe cooperation of the die F the outside diameter of the workpiece isreduced so that each section thereof will come to be turned Within itsplane, and the workpiece will thus obtain a substantially conical shape(Fig. 6). As soon as the stamp has entered so deep down into theworkpiece that the conical section c thereof will just come to pass outof the opposite end of the workpiece, this latter, which is stillretained at its rearward end by the upper edge of the die, has alreadyobtained a substantially cylindrical shape. During the entire portion ofthe pressing operation just described, the force imparted by the stampto the Workpiece, and which tends to pull the workpiece down into thedie, still remains approximately so big that it will come to becounterbalanced by the resistance which would have to be overcome whendrawing the workpiece through the die, so that neither the caseillustrated in either Figs. 8 or 4 is liable to arise. Toward the end ofthe motion executed by the stamp E, its collar 6 comes to bear upagainst the workpiece and forces it completely down into the die F (Fig.7). As soon as the stamp has carried out its return motion, the rim thuscompletely pressed in the course of a single working operation isremoved from the die by the ejector G.

Claim:

The method of producing solid drawn cylindrical rims out of flatcircular metal rings by the use of a drawing press having an annularfemale die and a stamp adapted to enter said annular die which consistsin placing the fiat metal ring upon the die of the drawing press andcausing the stamp of the drawing press which is provided with acylindrical part corresponding in width to the inside diameter of therim and a conical tapered part arranged in front thereof, to engage saidflat metal ring to draw said ring into said die, the ring having equalthickness and the width and outside diameter of the ring relatively tothe diameter of the bore of the die being so dimensioned that the ringis transformed to a finished cylindrical rim by only one stroke of thestamp.

The foregoing specification signed at Essen, Germany, this 19th day ofJanuary,

KARL BOHLE.

